I put a disc brake conversion on my 66 chevelle. I used a later model chevelle master and booster. I used a comb. valve off a late model chevy (monte SS, pickup, ect..) I have bled the brakes a million times. They all seem to come out good. However, without my booster hooked up, my pedal seems to feel ok. When I hook the booster up, my pedal get extremely soft and doesnt grab till the bottom of the stroke. When it does grab it seems to grab well enough. I dont believe it should work this way though. I would think the peddle would start to grab up top.

Did you do the swap from manual to power assist when doing the disc to drum swap?

Joe

I just did a complete brake job,might has well been a conversion but i have the same peddle problem.I finally am getting a better peddle after bleeding again.I think we still have air in the lines or a leak causing air to get sucked in.

I had a street rod that I switch over to power
dics brakes and had the same problem. I cured
my problem by going with a m/c with one bigger
size bore. :D